Tragic accidents and injuries due to improperly inflated tires and a large recall of tires in 2000 motivated Congress to take legislative action with regard to tire pressure monitoring in the automotive industry. Congress passed the Transportation Recall Enhancement, Accountability and Documentation (TREAD) Act in late 2000, which requires installation of tire pressure monitoring systems (TPMS). The National Highway Traffic Safety Administration (NHTSA) standard required automotive manufacturers to begin installing monitoring systems on light vehicles. The regulation impacts passenger cars, sport utility vehicles, pickup trucks and minivans. Accordingly, efforts continue to be made with respect to designing tire monitoring systems which provide better and more reliable tire data (e.g., temperature, pressure, etc.), to anticipate and prevent tire failures before they occur.
One common cause of tire problems is improperly inflated tires. A tire can lose up to half of its air pressure and not appear to be flat, and therefore unless the tire pressure is being checked on a regular basis, improper inflation can go unnoticed. Under-inflation can result in increased rolling resistance, tire stress, uneven tire wear, wheels being out of balance, decreased mileage, increased heat generation, etc. Over-inflation can cause uneven tire wear, a tire blow-out, and the like. An effective tire monitoring system can address these issues and others.
For example, one tire parameter that has a dramatic effect on tire performance is tire temperature during vehicle operation. Tire temperature can affect tire adhesion, tire wear characteristics, vehicle handling performance, fuel efficiency, and the like. Systems for monitoring vehicle tire parameters are known in the automotive industry. In such tire monitoring systems, tire temperature sensor(s) and radio frequency (RF) transmitters are mounted inside and in contact with each tire, typically adjacent the inflation valve stem. In one prior art system implementation, the tire temperature sensed by the temperature sensor is sent by a transmitter to a central receiver/controller located on-board the vehicle. The temperature information is delivered to the receiver/controller by RF signals and is subsequently converted to a pressure and conveyed to a vehicle operator, typically in the form of a visual display. This approach, however, has several potential shortcomings. First, the temperature sensor in contact with the tire measures only the immediate ambient temperature (a single temperature point), local to the sensor, so that an inaccurate or non-representative temperature reading acquired and thus correlated to an inaccurate pressure. Second, even though a vehicle occupant is provided with a warning light, often times the warning, is ignored and no subsequent action is taken.
In another prior art example, the tire pressure monitoring system uses pressure sensors in each tire for determining whether a tire is under-inflated, over-inflated or properly inflated. However, the monitoring system does not provide an indication of other potential problems such as the presence of imbedded foreign objects such as nails, treads that are excessively worn, delamination of the tire treads or impending catastrophic failure of the tire.
Thus, there exists a need for an improved system and method for remote monitoring of tire temperature, tire pressure and other tire parameters.